A) move three sodium ions out of a cell and two potassium ions into a cell while consuming an ATP for each cycle
B) moves three potassium ions out of a cell and two sodium ions into a cell while consuming 2 ATP in each cycle
C) moves three potassium ions out of a cell and two sodium ions into a cell while producing an ATP for each cycle
D) moves three sodium ions out of a cell and two potassium ions into a cell and generated an ATP in each cycle

A) move three sodium ions out of a cell and two potassium ions into a cell while consuming an ATP for each cycle

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The membranes of winter wheat are able to remain fluid when it is extremely cold by __.

A) increasing the percentage of cholesterol molecules in the membrane
B) passive diffusion
C) decreasing the number of hydrophobic proteins in the membraneD) increasing the percentage of unsaturated phospholipids in the membrane

D) increasing the percentage of unsaturated phospholipids in the membrane

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The force driving simple diffusion is ___, while the energy source for active transport is __.

According to the fluid mosaic model of cell membranes phospholipids ___.

A) frequently flip-flop from one side of the membrane to the otherB) can move laterally along the plane of the membrane
C) occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane
D) have hydrophilic tails in the interior of the membrane

B) can move laterally along the plane of the membrane

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For a protein to be an integral membrane protein, it would have to be __.

A) aphipathic, with at least one hydrophobic region
B) exposed on only one surface of the membrane
C) hydrophobic
D) hydrophilic

A) aphipathic, with at least one hydrophobic region

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Which of the following most accurately describes selective permeability?

A) There must be a concentration gradient for molecules to pass through a membrane
B) An input of energy is require for transport
C) Lipid-soluble molecules pass through a membraneD) Only certain molecules can cross a cell membrane

Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this most probably mean?

A) Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life
B) the concentration gradient; ADP
C) Cells of each domain evolved proton pumps independently when oceans became more acidic
D) The high concentration of protons in the ancient atmosphere must have necessitated a pump mechanism

A) Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life

(this multiple choice question has been scrambled)

Lysosomes maintain a pH of approximately 4.5-4.7, which is more acidic than the cytosol of the cell. Which of these is most likely responsible for maintaining the low pH of lysosomes?

A) Osmosis
B) A proton pump that pumps H+ out of the lysosomeC) A proton pump that pumps H+ into the lysosome
D) Passive diffusion